Teleconferencing permits more than two participants separated in time and space to communicate over telephone facilities using terminal equipment and/or bridging devices or services, such as the AT&T Alliance.RTM. Service. Typically, bridging services offer either a so-called "meet-me" service to which participants dial in to join a teleconference or a dial-out service in which, an operator/originator calls the participants of a teleconference. Bridging services connect each participant on a point-to-point basis to a bridging device which links the multiple parties into a teleconference. In spite of the multiple social and economic benefits of teleconferencing, its use, however, has been hampered by the paucity of features of the bridging devices and users' lack of control over transmission and reception of audio signals to, and from particular participants, respectively.
Aiming to provide a solution to that problem, Horn, in U.S. Pat. No. 5,113,431, issued May 12, 1992, disclosed a system that allows a teleconferencing user to select on a dynamic basis, particular participants to whom the user can listen or talk during a teleconference. The Horn system affords users some degree of control of the teleconference set-up. The Horn system does not provide a comprehensive solution to control the amplitude of audio signals generated by the participants of the teleconference.